CVE-2026-124440

Summary

Kyverno versions 1.19.1 and earlier contain an authorization bypass in the apiCall namespace clamp due to improper handling of percent-encoded characters in urlPath, allowing low-privilege users to issue cluster-scoped API requests as the admission-controller ServiceAccount. This enables cross-namespace resource reads and creation of mutating webhooks, leading to potential privilege escalation to cluster admin.

Exploitability

Exploitation requires authenticated access with permission to create namespaced Policies (PR:L) and involves crafting maliciously encoded urlPath values; public exploits exist, indicating low-to-moderate technical barrier for attackers with existing Kyverno access.

Blast radius

Successful exploitation allows full cluster compromise via unauthorized webhook creation and cross-namespace data exfiltration, affecting all tenants in multi-tenant clusters using Kyverno admission control.

Detection

Defenders should monitor for Policy resources with urlPath fields containing unusual percent-encoding patterns (e.g., %2f, %2F, %252f) that resolve to cluster-scoped endpoints or non-local namespaces when evaluated by the admission controller; also alert on unexpected use of cluster-scoped resources by the kyverno-admission-controller ServiceAccount in audit logs.

Prioritized remediation

Upgrade to Kyverno 1.19.2 or later, which patches the urlPath percent-escape handling flaw in the apiCall namespace clamp.

Analysis generated locally by garnet-coder (no data left the box). AI-assisted — verify against primary sources before acting.